Shutterstock/Matee Nuserm
An Asian-Australian moth becomes more sexually active under red light than under another colour of light or in the dark.
Dim red light appears to stimulate chemical changes in the antennae of male yellow peach moths (
Conogethes punctiferalis), making them more sensitive to the smells emitted by nearby females. This increases their copulation rates, says Wei Xiao at Southwest University in Chongqing, China.
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Xiao and his colleagues made the accidental discovery while studying the general behaviour of the moths, which invade orchards and spice farms across Asia and Australia.
To mimic natural light conditions in their laboratory, the scientists kept the lights on for 15 hours and turned them off for 9 hours per day. When they needed to work with the moths during the hours of darkness, they turned on red lights because scientists generally assume that insects can’t see red and react negligibly to it, says Xiao.